JPH0261255B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a dental dowel for use within a root canal to restore volume to a tooth root for crown restoration.

Conventionally, tooth dowels were made with a rigid structure that did not bend. Some of these have tapered threaded surfaces, as shown in Ellman US Pat. No. 4,239,489. Still others have elongated surfaces of continuous diameter over substantially their entire length, as shown in Clair U.S. Pat. . Some toothed dowels exhibit slots along the length of the sides, such as in Jastey U.S. Pat. No. 644,804. Best US Pat. No. 838,296 and the aforementioned Ellman patent disclose hollow dowels. Sellers US Patent No. 4234309 shows a wrench combination for use with tooth dowels, while Swiss Patent No.
562605 has essentially the same effect, with the dowel screw stopping short of reaching the tip of the screw where maximum holding force is obtained.

In each of the prior art examples described above, the nature of the tooth dowel is such that when it is screwed into the root canal,
The force exerted by the dowel screw on the engagement wall of the tooth exerts an outward expansion force on the tooth root, sometimes destroying the tooth root. If the tooth is destroyed, it cannot be repaired, so it is important to prevent this destruction when screwing the dowel into the tooth root, and also when the tooth is put into practical use after the tooth dowel and crown are attached to the tooth root. It is important to prevent tooth destruction.

Dental dowels of the type previously disclosed also result in fracture of the tooth root due to the lateral forces and stresses exerted on the dowel during mastication.

The problems of the prior art dental dowels mentioned above are sought to be solved by the present invention. The present invention provides a tooth dowel that can be screwed into the root canal with a wrench that is preset to apply a predetermined torque to the tooth dowel, thereby tightening the tooth into the root wall. Prevents the application of inappropriate forces and stresses, thus allowing the screwing of tooth dowels without destroying the teeth. When a dental dowel is inserted into a tooth, it is cemented and prevented from counter-rotational forces that would normally cause the dowel to be unscrewed from its home position on the tooth root. These counter-rotational forces are enhanced when the threaded foot of the tooth dowel expands normally and comes into closer and frictional engagement with the root canal thread. They are also
It is further exacerbated by irregularities in the walls of the teeth and by the presence of fixing cement in the gaps between the teeth.

The foregoing description, as well as the features, advantages and further objects of the invention, will be apparent from the following detailed description, in which preferred but illustrative embodiments according to the invention are set forth in conjunction with the accompanying drawings. , will be more fully evaluated.

In Figures 1 to 6, the tooth dowel is 31
It is indicated by 0. The dental dowel 310 includes a body 314 that extends integrally and in the same direction as a stem 312 at the distal or insertion end and a crown anchoring means 316 at the opposite or terminal end. Stem 312 has a distal or lead-in end that has legs 320 separated by a space in slot 324.
and a threaded portion 318 formed in each of 322.
The terminal is more tapered than the other terminals. Neither tapered insertion portion or tip 323 has any threads along its entire length and is angled to match the inclination angle of the introduction end of the root canal 19.

The function of the unthreaded tips 323 will become clear later, but for now we will focus on these tips 32.
3, the threaded portion 318 that forms a twist when the stem 312 is introduced into the root canal 19 is inserted into the root canal 19.
Note that we provide a matching means to match the . Furthermore, the tip 323 also has the function of matching, filling and occupying the entire depth and area of the pre-drilled root canal 19. Tip part 3
Since the angle 23 corresponds to the tapered part formed in the root canal 19 by the root canal preparation drill,
The tip 323 will almost completely fill the root canal end below the threaded portion 318. This allows for a longer contact area between the dowel 310 and the root canal 19, providing additional strength to the tooth 25 by providing more stress absorption and load distribution. Given.

The space in the slot 324 extends over a substantial portion of the stem 312 such that the legs 320 and 322 are each individually movable radially and tangentially relative to each other and self-tapping when screwing in the tooth dowel 310. As the threaded portion 318 forms the threads 317 within the tooth 25, it flexes and allows for relative movement as described above. slot 324
Although the space does not extend the entire length of the stem 312, the stem 312 and the main body 314 form a continuously extending discharge groove 327 of the slot 324, which is a discharge space.
Equipped with: The stem 312 has at least one
More than one discharge space 324, 327 is provided. Since the discharge spaces 324 and 327 communicate from the tip of the stem 312 to at least the distal end 326 of the main body 314, the discharge spaces serve as outlets for tooth fragments during screwing, and the dowel 310 is screwed into the root canal together with cement. Release the fluid pressure that develops under the dowel.

When the dowel 310 is screwed into the root canal 319 to form a thread, the slot 324 and drainage groove 3
The communicating discharge space consisting of 27 is the tooth root or tooth 25
It is always open at the top. As a result, CD cement, tooth shavings from screwing, fluids, air and other gases, pressure forming materials, etc. are exhausted into the atmosphere from the tip of the deepest part of the root canal 19, causing damage to the tooth root. Never.
In the discharge spaces 324 and 327, the dowel 310 is connected to the root canal 1.
Any hydrostatic pressure that gradually builds up from below around the tip 323 of the dowel as it is screwed into the tooth root canal is discharged from the root canal.

The crown anchoring means 316 is for anchoring the tooth crown to the dowel 310. Crown anchoring means 316
is a cross shape having a plurality of locking protrusions 332 in opposite directions. Each set of locking protrusions 332 are spaced apart from each other in the longitudinal direction of the crown anchoring means 316 by a separator or spacer 334. It will be obvious to those skilled in the art that the number of four protrusions is merely a matter of choice, and that the number is arbitrary. If the anchoring means 316 is larger than the height required for crown restoration, the length may be shortened by simply cutting off the protrusion 332 and spacer 334 by the amount that is deemed too large and unnecessary.

The stem 312 and body 314 are screwed into the root canal by forming a root canal thread 318 by self-tapping.
The sides of the screw are substantially parallel to and exactly match the external surfaces of self-tapping threaded portion 318 and dowel stem 312 and body 314.
Fill the root canal 319 with dental cement, apply it to the stem 312 and the main body 314, and tighten the threaded part 31.
It may be in intimate contact with all surfaces of 8.
Although the stem is shown as being divided into two legs, it is also within the scope of the present invention to divide the stem into multiple legs and have multiple similar evacuation or separation spaces 324. Once the stem 312 and main body 314 are coated with cement, preparation for screwing into the root canal 319 is completed. To introduce the dowel 310 into the root canal 19 , the dowel stem 312 of the tooth is first aligned with the root canal 319 . The initial rotation of the dowel to set the dowel and its stem 312 into the root canal 319 is performed with the fingers of the hand. Thereafter, a torque wrench is engaged with the top of the dowel 10, the handle of the torque wrench is rotated, and the dowel is screwed into the teeth 25 while self-tapping.

As the stem 312 and body 314 are gradually screwed into the root canal 319 and form the thread 317, anything trapped under the tip or insertion end of the stem, such as fluid, debris, gas or air, self-exerts. During tapping insertion, it is discharged to the outside air.
The spring-like connection between legs 320 and 322 follows and accommodates irregularities that occur as the legs bend radially inward toward each other and threaded portion 318 threadably engages root canal 319.

In this way, the destructive forces that occur during threaded engagement are absorbed by the rapid inward deflection of the legs as allowed by the slots 324 between the legs. The connecting portion 326 with memory acts like a spring that pushes outward, and always connects the stem 31.
2 and the threaded portion 318 of the body 314 are rapidly moved outward into full contact threaded engagement with the threads 317 formed in the root canal 319. This ensures the advantage of a perfect threaded engagement between the two threads 317 and the threaded part 318 at all times.

When the dowel 310 is screwed into the root canal 319, it is designed to ensure a sufficient thickness of dentin between the dowel and the outer wall of the tooth over its entire length. If there is no tapered tip 323, there may be a portion where sufficient dentin cannot be secured, and in that case, the strength of the tooth may decrease and fracture resistance may not be ensured.

The dowel 310 of the present invention solves the problem of tooth breakage by having its tip structure such that the minimum tooth wall thickness between the outer wall of the tooth and the nearest tip of the dowel is always at least 1 mm or less. I'm giving consideration. 6th
As can be seen, when the dowel 310 is screwed into the root canal 19, the space between the root canal 19 and the outer wall of the tooth 25 decreases toward the base of the tooth. Also, the tapered tip 323 is closer to the outer wall of the tooth than the rest of the dowel.

The distance between the tip of the dowel 310 and the outer wall of the tooth is 1
If the thickness is less than mm, the wall thickness at this closest point will not be sufficient to support and withstand the force that would destroy the tooth. Therefore, in order to provide the minimum tooth thickness and to allow the dowel to be inserted as deeply into the tooth as possible and to provide strength to the tooth, the dowel has a tapered tip 323, and the angle of the tapered part is set at the root of the tooth. This almost matches the angle of the tip of the root canal formed by the drill and tap used to open and thread the canal.
In this way, the deepest tip 32 of the dowel 310
3 is always located at a distance of at least 1 mm from the proximal outer wall of tooth 25, indicated by arrow 372 in FIG.

Although essential novel features of the invention have been described and pointed out in the preferred embodiment, various omissions, substitutions, and alterations may be made in the form, details, or handling of the illustrated devices without departing from the spirit of the invention. It will be appreciated that this can be done by one skilled in the art without delay.

[Brief explanation of the drawing]

Fig. 1 is a front view of a dowel showing an embodiment of the present invention, Fig. 2 is a plan view of the tooth crown locking part at the distal end of Fig. 1, and Fig. 3 is a line 10-10 in Fig. 1. Figure 4 is a cross-sectional view taken along line 11-11 in Figure 1, Figure 5 is a cross-sectional view taken along line 12-12 in Figure 1, and Figure 6 shows the dowel in Figure 1. It is a front view when it is screwed into the tooth root canal. Explanation of symbols of main parts, 310... Dowel, 31
2... Stem, 314... Main body, 316... Crown anchoring means, 318... Threaded portion, 320, 322...
...leg, 323...tip, 324...slot,
326... end, 327... drainage groove, 19... root canal, 25... tooth.

Claims (1)

[Scope of Claims] 1. A tooth dowel used in a tooth root canal, comprising: a stem having a longitudinally extending portion for insertion into the tooth root; and one longitudinal portion of the longitudinally extending portion of the stem. a slot formed in the stem and extending diametrically through the stem and further extending from the insertion end of the stem to form a plurality of relatively spaced movable feet; a space extending around and along the foot and cutting the tooth root and when the stem is screwed into the tooth root;
a tooth root cutting thread portion that facilitates screwing of the longitudinally extending portion into the tooth root by forming a thread in the tooth root that corresponds to the cutting screw of the stem; The other part in the longitudinal direction of the extending part is a holding part that holds the movable leg and gives appropriate rigidity to the movable leg, and the holding part is provided with a groove communicating with the space. The movable legs, which are movable with respect to each other when being screwed in, absorb the force generated by the cutting of the thread into the tooth root, and prevent the loading of forces that would destroy the tooth root, and the space is closed through the groove. The insertion end of the foot is tapered to correspond to the inclination of the root canal to provide at least a minimum tooth thickness of sufficient thickness and strength to prevent the loading of destructive forces on the tooth by venting the tooth root to the atmosphere. A tooth dowel that prevents destruction. 2. The tooth dowel according to claim 1, wherein the stem is substantially circular and has the same diameter over the entire length of its insertion into the root canal. Tooth dowel. 3. The tooth dowel according to claim 1, wherein a locking means for locking a tooth crown is provided at the end of the stem opposite to the longitudinally extending portion. A tooth dowel featuring 4. The tooth dowel according to claim 3, wherein the stem between the stem and the locking means is provided with an enlarged portion, and the enlarged portion has a cutting screw extension. A tooth dowel characterized by the fact that